我如何在vNext依赖注入创造构造认购 [英] How do I create Constructor Subscription in vNext Dependency Injection
问题描述
我使用的是一次性vNext应用试验。我试图做的是创建一个名为DataService的'，这会返回一些数据，然后创建一个使用DI采取一种IDataService参数作为构造对象的虚拟类。
I am experimenting with a throwaway vNext application. What I'm trying to do is create a dummy class called 'DataService' which will return some data, and then create objects which use DI to take an IDataService parameter as the constructor.
所以，我IDataService / DataService的定义是：
So my IDataService/DataService definitions are:
public interface IDataService
{
DateTime Created { get; }
}
public class DataService : IDataService
{
private DateTime created = DateTime.Now;
public DateTime Created
{
get { return created; }
}
}
在我的启动I类注册此为单：
In my startup class I register this as a singleton:
public void Configure(IApplicationBuilder app)
{
app.UseServices(services =>
{
services.AddSingleton<Data.IDataService, Data.DataService>();
});
而在我创建了一个类，我添加了IDataService接口作为构造依赖性：
And in a class I created, I add the IDataService interface as a constructor dependency:
internal class Constraint : IRouteConstraint
{
private readonly IDataService _dataService;
public Constraint (IDataService dataService)
{
_dataService = dataService;
}
public bool Match(....)
{
//call dataservice for match
}
}
与构造函数依赖这里的类是我想用它来获得在MVC动态路由的IRouteConstraint - 启动类code的最后一部分是这样的：
The class here with the constructor dependency is an IRouteConstraint which I'm trying to use to get dynamic routes in MVC - the final part of the startup class code is this:
app.UseMvc(routes => {
routes.MapRoute(name: "TestRoute", template: "{*constraints}", defaults: new { controller = "Test", action = "Index" }, constraints: new { constraint = new Constraint() }); //<--- how to construct using DI?
});
问题是，因为它缺少构造函数约束（）类不能被创建。所有的例子显示使用DI和控制器类的实例通过MVC的处理，以便为AUTOMAGIC我们不会第一眼看到一部分的控制器。
The issue is that the Constraint() class can't be created because it is missing the constructor. All the examples show a Controller using DI and the instantiation of the Controller classes are handled by MVC so that is part of the 'automagic' we don't see at first glance.
所以我的问题是：
- 我如何实例化约束对象，以便DI提供的DataService单的执行？
- 是我的问题，因为我在UseMvc方法配置方法尝试这一点，或者是我的问题比这更根本的？
我想我的思念越来越DI作为一个对象工厂提供我的对象，而不是试图以声明他们创造的某种方式。
I figure I'm missing some way of getting DI to act as an object factory to provide my objects instead of trying to declaratively creating them.
推荐答案
如果你想通过解决依赖注入的约束，你需要注册，第一：
If you're wanting to resolve your Constraint through the Dependency Injection, you'll need to register it, first:
services.AddTransient<Constraint>();
一旦你的IApplicationBuilder，您可以直接访问服务：
Once you have the IApplicationBuilder, you can access the services directly:
app.ApplicationServices.GetRequiredService<Constraint>();
当然，如果你不想要添加约束键入服务列表中，您仍然可以访问 IDataService 以同样的方式。
Of course, if you don't want to add your Constraint type to the services list, you can still access the IDataService the same way.
这里假设你有使用Microsoft.Framework.DependencyInjection; 在你启动的顶部声明;给你的其他的语法，我相信你做的。
This assumes you have using Microsoft.Framework.DependencyInjection; declared at the top of your Startup; given your other syntax, I believe that you do.
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